Bit odd that the BBC have thrown in that statement as if it's a fact that everyone knows!
Frankly, I'm not sure how they've worked that out.....typically we don't actually know what every club's comparative budgets have been until the club accounts come out i.e. not for a good while yet.
Unless they went and did some primary research - and then decided not to report at all on the results, just throw them into an occasional article....